Surgical anvil assemblies for surgical stapling instruments

ABSTRACT

A surgical anvil assembly for use with a circular stapling instrument includes an anvil center rod defining a longitudinal axis and an anvil head pivotally coupled to the anvil center rod and movable between a first operative condition and a second tilted condition. The anvil assembly further includes a locking assembly configured to selectively lock the anvil head in each of the first and second conditions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of U.S. patentapplication Ser. No. 16/275,514, filed on Feb. 14, 2019, which claimsthe benefit of, and priority to, U.S. Provisional Patent ApplicationNos. 62/649,278; 62/649,176; 62/649,341; 62/649,325; 62/649,304;62/649,267; 62/649,241; 62/649,227; 62/649,217; and 62/649,200, each ofwhich were filed on Mar. 28, 2018, the entire contents of each of whichare incorporated herein by reference.

BACKGROUND 1. Technical Description

The present disclosure generally relates to a surgical staplinginstrument and, more particularly, to a surgical anvil assembly for usewith a circular stapling instrument and having an anvil head capable ofpivoting or tilting to facilitate insertion and/or withdrawal of theanvil assembly relative to the operative site.

2. Background of Related Art

Circular stapling instruments for performing surgical procedures such asanastomoses, hemorrhoidectomies, and mucosectomies are well known. Thesedevices include an anvil assembly having a center rod and an anvil headsupported on the center rod. Typically, during a surgical procedure, thetool assembly of the circular stapling instrument is inserted into atubular section or sections of tissue to join the tissue sections orremove diseased or damaged tissue from within the tissue section. Inorder to minimize trauma to the tissue section, the anvil head may bepivotally supported on the center rod to reduce the profile of the anvilassembly during insertion and/or removal of the tool assembly from thetissue section. In some circular stapling instruments, a component isfractured during firing to permit tilting of the anvil head relative tothe center rod.

SUMMARY

In one aspect of the present disclosure, a surgical anvil assembly foruse with a circular stapling instrument is provided and includes ananvil center rod, an anvil head pivotally coupled to the anvil centerrod and movable between a first, operative condition and a second,tilted condition, a backup member slidably disposed within a recess ofthe anvil head and selectively engagable with the anvil center rod, anda locking assembly. The locking assembly includes an inner membersupported on an outer surface of the anvil head, an outer member movablycoupled to the inner member, and a post interconnecting the outer memberand the backup member. The outer member is configured to move relativeto the inner member between a first, proximal position, in which thelocking assembly maintains the backup member engaged with the anvilcenter rod to resist movement of the anvil head relative to the anvilcenter rod, and a second, distal position, in which the locking assemblymaintains the backup member disengaged from the anvil center rod toallow for movement of the anvil head relative to the anvil center rod.

In some aspects, the locking assembly may further include a lockingmember protruding outwardly from the inner member. The locking membermay be configured to engage the outer member when the outer member is inthe second, distal position to maintain the outer member in the second,distal position and, in turn, maintain the backup member disengaged fromthe anvil center rod.

The locking member may be configured to prevent movement of the backupmember from the first, proximal position toward the second, distalposition until a threshold, distally-oriented force has been applied tothe backup member.

In some aspects, the locking member may overlap with an inner lip of theouter member to resist distal movement of the outer member relative tothe inner member toward the second, distal position.

The locking member may include a first locking member extending radiallyoutward from a first side of the inner member, and a second lockingmember extending radially outward from a second side of the innermember. The first and second locking members may be engagable with aninner periphery of the outer member.

In some aspects, the locking member may include a detent configured toengage an inner periphery of the outer member when the outer member isin the second, distal position.

The outer member may include a lip protruding radially inwardly from theinner periphery thereof. The lip may be disposed proximally of thedetent when the outer member is in the first, proximal position, suchthat the detent resists movement of the outer member from the first,proximal position toward the second, distal position. The lip may bealigned with the detent when the outer member is in the second, distalposition, such that the detent resists movement of the outer member fromthe second, distal position toward the first, proximal position.

In some aspects, the detent may be configured to move radially inwardupon movement of the outer member toward the second, distal position.The detent may be configured to move radially outward upon movement ofthe outer member toward the first, proximal position.

The post may have a distal end disposed outside of the anvil head, anintermediary portion extending through the anvil head, and a proximalend disposed within the recess of the anvil head.

In some aspects, the anvil center rod may have a pair of arms supportingthe backup member thereon when the backup member is in the first,proximal position, such that the pair of arms prevent the backup memberfrom pivoting relative thereto.

The surgical anvil assembly may further include a cut ring positionedabout the backup member and secured thereto.

In some aspects, the surgical anvil assembly may further include a camlatch mounted to a post of the anvil head. The cam latch may beconfigured to normally bias the anvil head to the second, tiltedcondition.

Other features of the present disclosure will be appreciated from thefollowing description.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the presently disclosed surgical anvil assembliesfor incorporation into surgical circular stapling instruments aredescribed herein below with reference to the drawings, wherein:

FIG. 1 is a perspective view of an exemplary embodiment of a surgicalcircular stapling instrument including an embodiment of a surgical anvilassembly of the present disclosure;

FIG. 2 is a perspective view of the circular stapling instrumentillustrating a tool assembly including the anvil assembly separated froman elongate body of the circular stapling instrument;

FIG. 3 is a side cross-sectional view of the tool assembly illustratingthe anvil assembly mounted to the staple cartridge of a shell of thetool assembly;

FIG. 4 is a perspective view of the anvil assembly;

FIG. 5 is an exploded, perspective view of the anvil assembly;

FIG. 6 is a side cross-sectional view of the tool assembly illustratingthe anvil assembly mounted to the staple cartridge with an annular knifein an advanced position;

FIG. 7 is side cross-sectional view of the anvil assembly illustratingthe anvil head in a pivoted or tilted condition;

FIG. 8 is a side cross-sectional view of an embodiment of a surgicalanvil assembly for incorporation into the circular stapling instrumentof FIG. 1 ;

FIG. 9A is a first perspective view of an inner member of a lockingassembly of the anvil assembly of FIG. 8 ;

FIG. 9B is a second perspective view of the inner member of the lockingassembly;

FIG. 10 is a perspective view of an outer member of the locking assemblyof FIG. 8 ;

FIG. 11 is a side cross-sectional view of the anvil assembly of FIG. 8illustrating the locking assembly in a distal position;

FIG. 12 is a side cross-sectional view of the anvil assembly of FIG. 8illustrating the locking assembly in a proximal position;

FIG. 13 is a perspective view of another embodiment of a surgical anvilassembly for incorporation into the circular stapling instrument of FIG.1 ;

FIG. 14 is a side, perspective view of an anvil center rod of the anvilassembly of FIG. 13 ;

FIG. 15 is a perspective view of a resilient leg of the anvil assemblyof FIG. 13 ;

FIG. 16 is a side view of the resilient leg of FIG. 15 ;

FIG. 17 is a side view, with parts shown in phantom, of a trocar beinginserted into the anvil center rod of FIG. 14 ;

FIG. 18 is a perspective view, with parts shown in phantom, of thetrocar being inserted into the anvil center rod of FIG. 14 ;

FIG. 19 is a perspective view, with parts shown in phantom, of thetrocar fully inserted into the anvil center rod of FIG. 14 ;

FIG. 20 is a side cross-sectional view of another embodiment of asurgical anvil assembly for incorporation into the circular staplinginstrument of FIG. 1 ;

FIG. 21 is a perspective view of a proximal side of a ring assembly ofthe anvil assembly of FIG. 20 ;

FIG. 22 is a perspective view of a distal side of the ring assembly ofFIG. 21 ;

FIG. 23 is a side cross-sectional view of the anvil assembly of FIG. 20illustrating the ring assembly in a distal position;

FIG. 24 is a perspective view of components of another embodiment of asurgical anvil assembly for incorporation into the circular staplinginstrument of FIG. 1 ;

FIG. 25 is a perspective view of a proximal side of a ring assembly ofthe anvil assembly of FIG. 24 ;

FIG. 26 is a perspective view of a distal side of the ring assembly ofFIG. 25 ;

FIG. 27 is a partial, side cross-sectional view of the ring assembly ofFIG. 25 ;

FIG. 28 is a side cross-sectional view of the anvil assembly of FIG. 24illustrating the ring assembly in a proximal position;

FIG. 29 is a side cross-sectional view of the anvil assembly of FIG. 24illustrating the ring assembly in a distal position;

FIG. 30 is a side cross-sectional view of another embodiment of asurgical anvil assembly for incorporation into the circular staplinginstrument of FIG. 1 ;

FIG. 31 is a perspective view of a ring assembly of the anvil assemblyof FIG. 30 ;

FIG. 32 is a perspective, cross-sectional view of the ring assembly ofFIG. 31 ;

FIG. 33 is a perspective view of components of another embodiment of asurgical anvil assembly for incorporation into the circular staplinginstrument of FIG. 1 ;

FIG. 34 is a perspective view of an anvil head of the anvil assembly ofFIG. 33 ;

FIG. 35 is a perspective view of a ring assembly of the anvil assemblyof FIG. 33 ;

FIG. 36 is a side cross-sectional view of the ring assembly of FIG. 35 ;

FIG. 37 is a perspective view of a snap collar of the ring assembly ofFIG. 35 ;

FIG. 38A is perspective view of a proximal side of a backup member ofthe ring assembly of FIG. 35 ;

FIG. 38B is a perspective view of a distal side of the backup member ofFIG. 38A;

FIG. 39 is a side cross-sectional view of the anvil assembly of FIG. 33illustrating the ring assembly in a proximal position;

FIG. 40 is a side cross-sectional view of the anvil assembly of FIG. 33illustrating the ring assembly in a distal position;

FIG. 41 is a side cross-sectional view of another embodiment of asurgical anvil assembly for incorporation into the circular staplinginstrument of FIG. 1 ;

FIG. 42 is a perspective view of a distal portion of an anvil center rodof the anvil assembly of FIG. 41 ;

FIG. 43 is a side view of a linkage arm of a pivoting assembly of theanvil assembly of FIG. 41 ;

FIG. 44 a side cross-sectional view of the anvil assembly of FIG. 41illustrating the anvil assembly in a tilted condition;

FIG. 45 is a side cross-sectional view of another embodiment of asurgical anvil assembly for incorporation into the circular staplinginstrument of FIG. 1 ;

FIG. 46 is an enlarged view of a pivot member of the anvil assembly ofFIG. 45 ;

FIG. 47 is another side cross-sectional view of the anvil assembly ofFIG. 45 ;

FIG. 48 is an enlarged view of a cam latch of the anvil assembly of FIG.47 ;

FIG. 49 is a perspective view of another embodiment of a surgical anvilassembly for incorporation into the circular stapling instrument of FIG.1 ;

FIG. 50 is a perspective view of a proximal side of an anvil head of theanvil assembly of FIG. 49 ;

FIG. 51 is a side view of a cam latch of the anvil assembly of FIG. 49 ;

FIG. 52 is a side cross-sectional view of the anvil assembly of FIG. 49illustrating the anvil head in a tilted condition;

FIG. 53 is a side cross-sectional view of another embodiment of asurgical anvil assembly for incorporation into the circular staplinginstrument of FIG. 1 illustrating a ring assembly thereof in a proximalposition;

FIG. 54 is a side cross-sectional view of the surgical anvil assembly ofFIG. 53 illustrating the ring assembly thereof in a distal position; and

FIG. 55 is a side cross-sectional view of the surgical anvil assembly ofFIG. 53 illustrating the ring assembly after a retraction of an annularknife.

DETAILED DESCRIPTION

The presently disclosed anvil assemblies for use with various circularstapling instruments will now be described in detail with reference tothe drawings in which like reference numerals designate identical orcorresponding elements in each of the several views. In thisdescription, the term “proximal” is used generally to refer to thatportion of the instrument or surgical anvil assembly thereof that iscloser to a clinician, while the term “distal” is used generally torefer to that portion of the instrument or surgical anvil assemblythereof that is farther from the clinician. In addition, the termclinician is used generally to refer to medical personnel includingdoctors, nurses, and support personnel.

The exemplary surgical stapling instrument includes a handle assembly,an elongate body or adapter, and a tool assembly coupled to the adapter.The tool assembly includes a shell assembly and an anvil assemblymounted with respect to the shell assembly. The anvil assembly includesa center rod releasably couplable to the elongate body and an anvil headwhich is pivotally coupled to the center rod. The anvil head is movablebetween a pre-fired, untilted or operative condition and a post-fired,tilted or pivoted condition. The anvil head is locked in the pre-firedposition until an annular knife of the tool assembly is advanced, whichfrees the anvil head to pivot or rotate relative to the center rodtowards the pivoted condition. The present disclosure provides, interalia, various embodiments of mechanisms for unlocking the anvil headfrom the anvil center rod, and various embodiments of mechanisms thatdrive the rotation of the anvil head upon being unlocked from the centerrod.

Referring initially to FIGS. 1-2 , an exemplary embodiment of a circularstapling instrument for incorporating the surgical anvil assemblies ofthe present disclosure is illustrated and shown generally as circularstapling instrument 10. The circular stapling instrument 10 includes ahandle 12, an elongate body or adapter 14 extending from the handle 12,and a tool assembly 16 coupled to the adapter 14. The handle 12 may beelectrically powered including a motor and associated gears and linkagesto control operation of the stapling instrument 10. The handle 12incorporates a grip 18 and a plurality of actuation buttons 20 which maybe activated to control various functions of the stapling instrument 10including, e.g., approximation of the tool assembly 16 and firing ofstaples. The grip 18 may support a battery pack (not shown) which powersthe handle 12. In embodiments, the circular stapling instrument 10 maybe powered via an external power source.

In embodiments, the adapter 14 is releasably coupled to the handle 12and includes a plurality of drive mechanisms (not shown) that translatepower from the handle 12 to the tool assembly 16 in response toactuation of the actuation buttons 20 to effect operation, e.g.,approximation and firing, of the tool assembly 16. The adapter 14 alsoincludes an anvil retainer 22 or trocar that extends from a distalportion of the adapter 14 and is movable between retracted and advancedpositions. The anvil retainer 22 is couplable to the tool assembly 16.Commonly assigned U.S. Pat. Nos. 9,247,940; 9,055,943; and 8,806,973,and 9,629,633 disclose exemplary embodiments of powered handles andadapters suitable for use with the stapling instrument 10, and which areincorporated in their respective entireties by reference herein.Alternately, the elongate body or adapter 14 may be non-removablysecured to the handle 12.

It is also envisioned that the handle 12 may be manually powered.Examples of manually powered handle assemblies are described in commonlyassigned U.S. Pat. Nos. 8,789,737; 8,424,535; and 8,360,295 which areincorporated in their respective entireties by reference herein.

Referring to FIGS. 3-5 , in conjunction with FIG. 2 , the tool assembly16 includes a shell 24 and a surgical anvil assembly 26 releasablymounted to the shell 24. The shell 24 supports an annular staplecartridge 28 and an annular knife 30 internal of the staple cartridge28. The staple cartridge 28 includes a plurality of staple receptacles32 each accommodating an individual staple 34 and a staple pusher 36 forejecting the staples 34 from the staple cartridge 28 upon firing of theinstrument 10.

The anvil assembly 26 shares common features with the anvil assemblydisclosed in commonly assigned U.S. Pat. No. 8,540,132, the entirecontents of which are incorporated by reference herein. As best depictedin FIGS. 3-5 , the anvil assembly 26 includes an anvil center rod 38 andan anvil head 40 pivotally mounted to the anvil center rod 38. The anvilhead 40 is adapted to pivot between a first operative condition asdepicted in FIGS. 4 and 6 , and a second pivoted or tilted condition asdepicted in FIG. 7 . The anvil center rod 38 includes a pair of distalspaced arms 42 having transverse bores 44 that receive a pivot member,such as, for example, a pivot pin 66, therethrough. The anvil head 40 ispivotably coupled to the distal spaced arms 42 via the pivot pin 66.

The anvil assembly 26 further includes a plunger 46, a plunger spring48, and a cam latch or cam plate 50. The plunger 46 is at leastpartially received within the anvil center rod 38, e.g., between thespaced arms 42, and is spring biased in a distal direction by theplunger spring 48. The plunger 46 includes a plunger finger 52, whichengages the cam latch 50 to provide a distally-oriented force on the camlatch 50.

The anvil head 40 includes a housing 54 defining a recess 70 therein,and a post 56 extending proximally from a center of the housing 54. Thehousing 54 has an anvil tissue contact surface 58 defining a pluralityof staple deforming pockets 72. The post 56 of the anvil head 40includes a pair of spaced post arms 60 defining a slot 62 and transversebores 64 extending through the spaced post arms 60. As briefly mentionedabove, the anvil center rod 38 is at least partially positioned aboutthe post 56 and coupled to the anvil head 40 through the pivot member 66which extends through respective transverse bores 44, 64 of the distalspaced arms 42 of the anvil center rod 38 and the post 56 to pivotallycouple the anvil head 40 to the anvil center rod 38. In addition, thecam latch 50 is received within the slot 62 of the post 56 and coupledto the anvil center rod 38 and the post 56 via the pivot member 66 whichextends through a pin opening 68 of the cam latch 50.

Referring now to FIGS. 4-6 , the anvil assembly 26 further includes abackup member 76 and a cut ring 78 attached thereto. The backup member76 and the cut ring 78 are moved together within the recess 70 of theanvil head 40 upon application of a force thereto, e.g., duringadvancement of the annular knife 30 of the tool assembly 16 duringfiring of the instrument 10. The backup member 76 includes an annularbody 79 and a pair of diametrically opposed fingers 98 extendingradially inward from the annular body 79. The annular body 79 of thebackup member 76 is axially movable, but pivotally fixed within therecess 70 of the anvil head 40.

The fingers 98 are engaged by the spaced arms 42 of the anvil center rod38 to prevent the backup member 76 from moving in a proximal directionand to maintain the anvil head 40 in the operative condition (e.g.,untilted) until the annular knife 30 is actuated. More specifically,when the backup member 76 is in the proximal position, as shown in FIG.3 , the fingers 98 of the backup member 76 sit on or abut a distalsurface of the spaced arms 42 of the anvil center rod 38, wherebyrocking or pivotal movement of the anvil head 40 relative to the anvilassembly 26 is prevented. Pivotal movement of the anvil head 40 relativeto the anvil center rod 38 is permitted only after the fingers 98 aredistally spaced from the arms 42 of the anvil center rod 38.

The backup member 76 further includes a pair of diametrically opposedcam shelves 99 extending radially inward from the annular body 79. Thecam shelves 99 capture the cam latch 50 therebetween to rotationally fixthe cam latch 50 to the backup member 76. In this way, as the cam latch50 rotates or pivots, so does the backup member 76 and the anvil head 40as a whole. The backup member 76 may be formed from a hard material suchas metal, although other materials of construction are envisioned.

The cut ring 78 of the anvil assembly 26 includes a disc-shaped annularbody 104 defining a central aperture 106 for reception of the backupmember 76. Thus, movement of the backup member 76 between the untiltedand tilted conditions causes corresponding movement of the cut ring 78.In embodiments, the cut ring 78 may be formed through a molding process,e.g., an injection molding process, and may be fabricated from amaterial having a durometer which permits the annular knife 30 to piercethrough the annular body 104 and bottom out against the backup member76. Suitable materials of the cut ring 78 include polypropylene orpolyester. Other materials are contemplated.

Prior to firing of the stapling instrument 10, the backup member 76 isin its retracted or proximal position with the cut ring 78 secured tothe backup member 76 in the aforedescribed manner. With the backupmember 76 in the proximal position, the inwardly extending fingers 98 ofthe backup member 76 are engaged by the spaced arms 42 (FIG. 4 ) of theanvil center rod 38, such that the anvil head 40 is retained in theoperative condition. As described above, the plunger finger 52 of theplunger 46 of the anvil center rod 38 is positioned to urge the camlatch 50 and the anvil head 40 about the pivot member 66 towards thetilted condition (FIG. 7 ). However, the anvil head 40 is prevented frompivoting until the annular knife 30 is advanced to unlock a lockingassembly 100 (FIGS. 4, 5, and 8-12 ) of the surgical anvil assembly 26,as will be described.

With reference to FIGS. 8-12 , the surgical anvil assembly 26 mayfurther include a locking assembly 100 for selectively locking the anvilhead 40 in each of the first, operative condition, and the second,tilted condition. The locking assembly 100 replaces the deformableretainer members of the prior art, such as the retainer member 127described in U.S. Pat. No. 9,532,781, the entire contents of which beingincorporated by reference herein. The deformable retainer memberstypically support the backup member 76 in the proximal position anddeform upon advancement of the backup member 76 to allow for tilting ofthe anvil head 40. Due to the absence of the deformable retainer in thepresent embodiment, the anvil head 40 is capable of repeated movementbetween the untilted and tilted conditions.

The locking assembly 100 generally includes an annular inner member orhousing 102, an annular outer member 104 surrounding the inner member102, and a pair of locking elements 106 a, 106 b movably coupled to theinner member 102. In embodiments, the inner and outer members 102, 104may assume any suitable shape, such as, for example, ring-shaped,squared, triangular, or the like. The inner member 102 is fixedlysupported on a distally-facing outer surface 41 of the anvil head 40.The anvil head 40 may have a plurality of holes 108 (FIG. 8 ) definedtherethrough for receipt of fasteners (not explicitly shown) thatfixedly attach the inner member 102 of the locking assembly 100 to theanvil head 40. The inner member 102 defines a plurality of passageways110 defined transversely therethrough for housing a respective lockingelement 106 a or 106 b. While four passageways 110 are illustrated, itis contemplated that the inner member 102 may have more or less thanfour passageways 110 for accommodating a respective number of lockingelements 106 a, 106 b.

The locking elements 106 a, 106 b are received in the passageways 110 ofthe inner member 102 and are arranged in diametrical opposition to oneanother. The locking elements 106 a, 106 b may be ball detents thatprotrude radially outward from an outer periphery 112 of the innermember 102. In embodiments, the locking elements 106 a, 106 b may be anysuitable biasing member that is resiliently, radially-outwardly biased.In embodiments, the locking elements 106 a, 106 b may remain fixedrelative to the inner member 102 whereas the outer member 104 may beflexible, such that the outer member 102 flexes outwardly uponcontacting the locking element 106 a, 106 b as the outer member 104slides along the inner member 102, as will be described.

The outer member 104 of the locking assembly 100 surrounds the innermember 102 and is slidable relative thereto along a longitudinal axis“X” between a first, proximal position (FIG. 12 ), in which the outermember 104 abuts the outer surface 41 of the anvil head 40, and asecond, distal position (FIG. 11 ), in which the outer member 104 isdistally spaced from the outer surface 41 of the anvil head 40. Theouter member 104 has an inner surface or inner periphery 114 that isadjacent to and surrounds the outer periphery 112 of the inner member102. The inner periphery 114 of the outer member 104 has a lip or ledge116 protruding radially inward therefrom for selective interaction withthe locking elements 106 a, 106 b.

More particularly, in the first, proximal position (FIG. 12 ), the lip116 of the outer member 104 is disposed proximally of an outer surfaceof the locking elements 106 a, 106 b while also overlapping therewith.Due to the lip 116 of the outer member 104 overlapping the lockingelements 106 a, 106 b, the locking elements 106 a, 106 b resist distalmovement of the outer member 104 relative to the inner member 102. Todistally move the outer member 104 of the locking assembly 100, athreshold force oriented in the distal direction must be applied to theouter member 104 to overcome the spring force of the locking elements106 a, 106 b. Upon application of the threshold force, the lockingelements 106 a, 106 b are moved radially inward relative to the innermember 102, allowing the lip 116 of the outer member 104 to pass overthe locking elements 106 a, 106 b.

When the outer member 104 is in the second, distal position (FIG. 11 ),the locking elements 106 a, 106 b and the lip 116 of the outer member104 are engaged and aligned along a transverse axis. Since the lockingelements 106 a, 106 b exhibit an outwardly-oriented spring bias, the lip116 of the outer member 104 and the locking elements 106 a, 106 b arefrictionally engaged with one another, thereby resisting movement of theouter member 104 from the second, distal position until the thresholdforce is applied in the proximal direction.

The locking assembly 100 further includes a plurality of posts or rods118 interconnecting the inner member 102 of the locking assembly 100 andthe backup member 76. The posts 118 are circumferentially spaced fromone another and extend downwardly (e.g., proximally) from the outermember 104. The posts 118 have a distal end 118 b attached to or formedwith the outer member 104, an intermediary portion 118 c extendingthrough a respective hole 108 defined through the anvil head 40, and aproximal end 118 a disposed within the recess 70 of the anvil head 40.The proximal end 118 a of each of the posts 118 is fixed to the backupmember 76, such that the backup member 76 moves with the outer member104 as the outer member 104 moves relative to the inner member 102.Accordingly, as the outer member 104 moves from the first, proximalposition (FIG. 12 ) toward the second, distal position (FIG. 11 ), thebackup member 76 moves deeper into the recess 70 of the anvil head 40and out of engagement with the distal spaced arms 42 of the anvil centerrod 38.

In operation, the backup member 76 with the cut ring 78 is maintained inthe recess 70 in the proximal position by the locking assembly 100. Inparticular, the locking elements 106 a, 106 b resist distal movement ofthe outer member 104 of the locking assembly 100 relative to the innermember 102 of the locking assembly 100. Since the backup member 76 isfixed to the outer member 104 via the posts 118 of the locking assembly100, distal movement of the backup member 76 toward the distal positionis also resisted.

When the anvil head 40 and the staple cartridge 28 (FIG. 3 ) of theshell 24 are approximated, the stapling instrument 10 may be fired toadvance the annular knife 30 within the shell 24 from a retractedposition recessed within the shell 24 to an advanced position extendinginto the cut ring 78 of the anvil assembly 26. As the annular knife 30engages the cut ring 78, the cut ring 78 and the backup member 76 exerta distally-oriented force on the outer member 104 of the lockingassembly 100 via the posts 118 of the locking assembly 118. Uponapplying the threshold force on the outer member 104, the lockingelement(s) 106 a, 106 b are forced radially-inward into the respectivepassageways 110 of the inner member 102, allowing the lip 116 of theouter member 104 to pass over the locking elements 106 a, 106 b as thebackup member 76 is advanced to the second, distal position within therecess 70 of the anvil head 40, as shown in FIG. 11 . Once the backupmember 76 moves towards its second position, the lip 116 of the outermember 104 and the locking elements 106 a, 106 b frictionally engage oneanother to selectively fix the outer member 104 and, in turn, the backupmember 76 in the second, distal position.

As the backup member 76 is moved toward its distal position, the fingers98 (FIGS. 4 and 5 ) of the backup member 76 disengage the distal spacedarms 42 of the anvil center rod 38, freeing the anvil head 40 to pivotrelative to the anvil center rod 38. With the anvil head 40 free torotate, the plunger spring 48 (FIG. 6 ) urges the plunger 46 in a distaldirection whereby the plunger finger 52 engages the cam latch 50 torotate the cam latch 50 and the anvil head 40 about the pivot member 66to permit the anvil head 40 to assume the second tilted conditiondepicted in FIG. 7 .

After the anvil head 40 is moved to the tilted condition, the anvil head40 may be manually moved back towards the first, operative condition.After moving the anvil head 40 back to the first, operative condition(e.g., untilted), the backup member 76 may also be reset to its proximalposition. To move the backup member 76 to the proximal position, aproximally-oriented threshold force may be manually applied to the outermember 104 of the locking assembly 100, which overcomes the staticfriction between the lip 116 of the outer member 104 and the lockingelements 106 a, 106 b, whereby the outer member 104 moves proximallyrelative to the inner member 102. Due to the interconnection between theouter member 104 and the backup member 76 via the posts 118, the backupmember 76 moves proximally with the outer member 104 back toward theproximal position.

Upon re-entering the proximal position, the fingers 98 (FIGS. 4 and 5 )of the backup member 76 re-engage the distal spaced arms 42 of the anvilcenter rod 38, thereby stabilizing the anvil head 40 in the first,operative condition. It is contemplated that this process of selectivelymoving the anvil head 40 relative to the anvil center rod 38 may berepeated indefinitely.

With reference to FIGS. 13-19 , another embodiment of a surgical anvilassembly 126 is illustrated, similar to the anvil assembly 26 describedabove. Due to the similarities between the anvil assembly 126 of thepresent embodiment and the anvil assembly 26 described above, only thoseelements of the anvil assembly 126 deemed necessary to elucidate thedifferences from anvil assembly 26 will be described in detail.

With specific reference to FIGS. 13 and 14 , the anvil assembly 126includes an anvil center rod 138 and an anvil head 140, similar to theanvil head 40 described above. The anvil head 140 is pivotally mountedto the anvil center rod 138. The anvil center rod 138 may include a pairof distal spaced arms 142 and an elongated proximal body portion 144extending proximally from the pair of distal spaced arms 142. The distalspaced arms 142 define transverse bores 143 through a distal end thereoffor receiving a pivoting member (not explicitly shown), similar to thepivot member 66 described above. The proximal body portion 144 of theanvil center rod 138 is configured to releasably couple to an anvilretainer or trocar, such as, for example, the anvil retainer 22 shown inFIG. 2 . A detailed description of an anvil retainer may be found inU.S. Pat. No. 7,364,060, the entire contents of which being incorporatedby reference herein.

The proximal body portion 144 of the anvil center rod 138 defines a pairof diametrically opposed slots 150 a, 150 b. The slots 150 a, 150 bextend proximally from a location adjacent a proximal end of the distalspaced arms 142 and terminate distally of a proximal end of the proximalbody portion 144. The slots 150 a, 150 b are dimensioned for receipt ofa pair of legs 152, 154 configured to releasably capture the anvilretainer 22 therebetween, as will be described below.

With reference to FIGS. 15-19 , the legs 152, 154 of the anvil centerrod 138 are received within a respective slot 150 a, 150 b in theproximal body portion 144 of the anvil center rod 138. Each of the legs152, 154 is fabricated from a material that allows the legs 152, 154 toflex about proximal ends 152 a, 154 a thereof in a spring-like manner.It is contemplated that the thickness of the legs 152, 154 may beincreased or decreased to adjust the flexibility thereof. Distal ends152 b, 154 b of the legs 152, 154 are attached to an inner periphery 156of the proximal body portion 144 via, for example, laser welding,whereas proximal ends 152 a, 154 a of the legs 152, 154 are free topivot relative to the respective distal end 152 b, 154 b.

In embodiments, the legs 152, 154 may be attached to the proximal bodyportion 144 along any suitable location of the legs 152, 154 using anysuitable fastening method. As can be appreciated, adjusting the locationat which the legs 152, 154 are attached to the proximal body portion 144changes the force required to flex the legs 152, 154. The proximal ends152 a, 154 a of the legs 152, 154 include a tab or detent 158, 160 thatextends radially inward. The detents 158, 160 are configured for snapfit engagement with a lip 23 defined by a proximal end of the trocar 22,as will be described in further detail below.

Each of the legs 152, 154 has an outer profile that matches the outerprofile of the proximal body portion 144 so that the legs 152, 154 donot protrude outwardly from the proximal body portion 144. Each of thelegs 152, 154 has an inner profile that substantially matches an outerprofile of the trocar 22. As such, when the legs 152, 154 are disposedwithin the respective slots 150 a, 150 b of the proximal body portion144, the legs 152, 154 cooperatively define a cavity 162 therebetweendimensioned for receipt of the trocar 22.

During manufacture, the legs 152, 154 are received within a respectiveslot 150 a, 150 b of the proximal body portion 144, and the distal end152 b, 154 b of each of the legs 152, 154 is welded (e.g., laser welded)to the inner periphery 156 (FIG. 18 ) of the proximal body portion 144.As shown in FIGS. 17 and 18 , the trocar 22 is distally advanced, in thedirection indicated by arrows “A” in FIG. 18 , through the proximal bodyportion 144, whereby a tapered outer surface 25 of the base of thetrocar 22 engages the detents 158, 160 at the proximal end 152 a, 154 aof the legs 152, 154, causing the legs 152, 154 to flex outwardly. Asshown in FIG. 19, distal advancement of the trocar 22 is continued untilthe lip 23 defined at the base of the trocar 22 passes over the detents158, 160 of the legs 152, 154, such that the detents 158, 160 snap intoplace proximally of the lip 23 of the trocar 22, capturing the trocar 22in the cavity 162 defined between the legs 152, 154. Theinwardly-oriented resilient bias of the legs 152, 154 axially fixes thetrocar 22 within the proximal body portion 144.

With reference to FIGS. 20-23 , another embodiment of a surgical anvilassembly 226 is illustrated, similar to the anvil assemblies describedabove. Due to the similarities between the anvil assembly 226 of thepresent embodiment and the anvil assemblies described above, only thoseelements of the anvil assembly 226 deemed necessary to elucidate thedifferences from the other anvil assemblies will be described in detail.

The anvil assembly 226 includes an anvil center rod 238, an anvil head240 pivotally mounted to the anvil center rod 238, and a ring assembly250 for selectively unlocking the anvil head 240 from the anvil centerrod 238. The anvil head 240 is configured to pivot relative to the anvilcenter rod 238 between a first operative condition and a second pivotedor tilted condition. The anvil head 240 defines a recess 270 thereinhaving a post 256 of the anvil head 240 extending proximally therefrom.The post 256 of the anvil head 240 is pivotally coupled to a distal endof the anvil center rod 238.

The ring assembly 250 is received within the recess 270 defined in theanvil head 240 and generally includes a backup member 276 and a cut ring278 disposed about and secured to the backup member 276. The ringassembly 240 is movable within the recess 270 of the anvil head 240 uponapplication of a force thereto, e.g., during advancement of an annularknife, such as, for example, the annular knife 30 shown in FIGS. 3 and 6. The backup member 276 of the ring assembly 250 has a ring body 279 andan annular lip 252 extending radially outward from a distal end of thering body 279 to support the cut ring 278 thereon. The ring body 279defines a central opening 294 for reception of the post 256 of the anvilhead 240. The central opening 294 is dimensioned to allow movement ofthe backup member 276 about the post 256 from a pre-fired, retracted orproximal position (FIG. 20 ) to a post-fired, advanced or distalposition (FIG. 23 ) within the recess 70 of the anvil head 40.

The backup member 276 further includes a pair of diametrically opposedfingers 298 extending inwardly from the ring body 279 into the centralopening 294. The fingers 298 are engaged by a distal end of the anvilcenter rod 238 to prevent the backup member 276 from moving in aproximal direction and to maintain the anvil head 40 in the operativecondition (e.g., untilted), in a similar manner described above. Pivotalmovement of the anvil head 240 relative to the anvil center rod 238 ispermitted only after the fingers 298 are distally spaced from the distalend of the anvil center rod 238. The backup member 276 is restrictedfrom moving distally out of the proximal position by a frangible portion254 of the cut ring 278, as will be described below. The backup member276 may be formed from a hard material such as metal, although othermaterials of construction are envisioned.

The cut ring 278 of the ring assembly 250 includes a disc-shaped annularbody 257 defining a central aperture 258 for reception of the backupmember 276. The annular body 257 may be press fit onto the backup member276. Thus, movement of the backup member 276 between proximal and distalpositions causes corresponding movement of the cut ring 278. Inembodiments, the cut ring 278 may be formed through a molding process,e.g., an injection molding process, and may be fabricated from amaterial having a durometer which permits the annular knife 30 to piercethrough the annular body 257 and bottom out against the annular lip 252of the backup member 276. In embodiments, the cut ring 278 may befabricated from a material that prevents advancement of the annularknife 30 therethrough and is instead coated with a material that permitsadvancement of the annular knife 30 therethrough. Suitable materials forthe cut ring 278 include polytetrafluoroethylene, polypropylene orpolyester. Other materials are contemplated.

As best shown in FIG. 21 , the cut ring 278 includes a plurality ofpockets 258 formed in a bottom or proximal surface 260 thereof. Thepockets 258 are illustrated as having a curved shape, but it iscontemplated that the pockets 258 may assume any suitable shape. The cutring 278 further includes a plurality of frangible portions or legs 254extending distally from a top or distal surface 262 of the annular body257 of the cut ring 278. As shown in FIG. 20 , the frangible legs 254suspend the annular body 257 of the cut ring 278 in the recess 270 ofthe anvil head 240 to maintain the ring assembly 250 in the proximalposition. The frangible legs 254 may have a curved shape and arepositioned directly over a respective pocket 258. The frangible legs 254are configured to deform (e.g., collapse) into the respective pocket 258upon application of a distally-oriented threshold force on the ringassembly 250.

To facilitate deformation of the frangible legs 254, the distal surface262 of the annular body 257 of the cut ring 278 defines a pair ofannular indentations 264 disposed on opposite sides of the frangiblelegs 254. The indentations 264 may have an arcuate, V-shaped, or anysuitable cross-sectional configuration. The frangible legs 254 of thecut ring 278 may be fabricated from the same or a different material asthe annular body 257 of the cut ring 278. For example, the frangiblelegs 254 may be fabricated from polytetrafluoroethylene, polypropyleneor polyester.

In operation, prior to firing of the annular knife 30 (FIGS. 3 and 6 ),the ring assembly 250 (including the backup member 276 and the cut ring278) is in its retracted or proximal position. In the proximal position,the frangible legs 254 of the cut ring 278 are in engagement with aninner surface 272 of the anvil head 240, thereby maintaining the ringassembly 250 in the proximal position, as shown in FIG. 20 . With thering assembly 250 in the proximal position, the inwardly extendingfingers 298 of the backup member 276 are engaged by the anvil center rod238, such that the anvil head 240 is retained in the first, operativecondition and prevented from pivoting relative to the anvil center rod238.

When the annular knife 30 (FIGS. 3 and 6 ) is advanced, the annularknife 30 engages the annular body 257 of the cut ring 278 of the ringassembly 250. The annular knife 30 pierces the annular body 257 of thecut ring 278 and ultimately engages the annular lip 252 of the backupmember 276. The force applied by the annular knife 30 on the ringassembly 250 is transferred to the frangible legs 254 of the cut ring278, which are compressed between the annular body 257 of the cut ring278 and the inner surface 272 of the anvil head 240. Upon the annularknife 30 applying a distally-oriented threshold force on the ringassembly 250, the frangible legs 254 of the cut ring 278 detach or breakfrom the annular body 257 of the cut ring 278 along the annularindentations 264.

With the frangible legs 254 of the cut ring 278 detached from theannular body 257 of the cut ring 278, a continued distally-orientedforce on the ring assembly 250, applied via the annular knife 30, drivesthe annular body 257 of the cut ring 278 and the backup member 276distally, whereby the frangible legs 254 of the cut ring 278 collapse orfall into the respective pockets 258 in the annular body 257 of the cutring 278, as shown in FIG. 23 . As the ring assembly 250 is advancedtoward the distal position, the inwardly extending fingers 298 of thebackup member 276 disengage from the arms of the anvil center rod 238,allowing for the anvil head 240 to pivot relative to the anvil centerrod 238. It is contemplated that the anvil head 240 may pivotautomatically relative to the anvil center rod 238 in the same mannerdescribed above. In embodiments, the anvil head 240 may be pivotedautomatically or manually via any suitable mechanism, such as thosemechanisms described in the patents incorporated by reference herein.

With reference to FIGS. 24-29 , another embodiment of a surgical anvilassembly 326 is illustrated, similar to the surgical anvil assembliesdescribed above. Due to the similarities between the anvil assembly 326of the present embodiment and the anvil assemblies described above, onlythose elements of the anvil assembly 326 deemed necessary to elucidatethe differences from the previously described anvil assemblies will bedescribed in detail.

The anvil assembly 326 generally includes an anvil center rod (notshown), similar to the anvil center rods described above, an anvil head340 configured to be pivotally mounted to the anvil center rod, and aring assembly 350 configured to selectively unlock the anvil head 340from the anvil center rod. The anvil head 340 is configured to pivotrelative to the anvil center rod between a first operative condition anda second pivoted or tilted condition.

The anvil head 340 defines a recess 370 (FIG. 28 ) therein having a post356 of the anvil head 340 extending proximally therefrom. The post 356of the anvil head 340 is configured to be pivotally coupled to a distalend of the anvil center rod. The recess 370 of the anvil head 340 isdimensioned for slidable receipt of the ring assembly 350. The anvilhead 340 includes an annular, inner peripheral surface 372 thatpartially defines the recess 370, and an inner race or catch 374 thatextends radially inward from the inner peripheral surface 372. The innerrace 374 resists, without preventing, distal movement of the ringassembly 350 through the recess 370 of the anvil head 340.

The ring assembly 350 generally includes a backup member 376, similar tothe backup members described above, a ring cup 352 nested in the backupmember 376, and a cut ring 378 nested in the ring cup 352. The ringassembly 350 is moved within the recess 370 of the anvil head 340 uponapplication of a force thereto, e.g., during advancement of an annularknife 30 (FIGS. 28 and 29 ). The backup member 376 defines a centralopening 394 for reception of the post 356 of the anvil head 340. Thecentral opening 394 is dimensioned to facilitate movement of the backupmember 376 about the post 356 from a pre-fired, retracted or firstposition to a post-fired, advanced or second position within the recess370 of the anvil head 340. The backup member 376 is retained in theproximal position by the inner race 374 of the anvil head 340, whichsupports the ring cup 352 in the proximal position (FIG. 28 ), as willbe described.

The backup member 376 includes a pair of diametrically opposed fingers398 extending inwardly into the central opening 394. The fingers 398 areengaged by the anvil center rod to prevent the backup member 376 frommoving in a proximal direction and to maintain the anvil head 340 in theoperative condition (e.g., untilted). Pivotal movement of the anvil head340 relative to the anvil center rod is permitted only after the fingers398 are distally spaced from the anvil center rod.

The backup member 376 of the ring assembly 350 further includes anannular wall or ring 354, and a disc-shaped platform 357 extendingradially outward from a distal portion of the annular wall 354. Theannular wall 354 has a lip 358 extending radially inward from a proximalportion thereof. The lip 358 is configured to engage (e.g., via snap-fitengagement) the ring cup 352 to retain the ring cup 352 with the backupmember 376. The backup member 376 may be formed from a hard materialsuch as metal, although other materials of construction are envisioned.

The ring cup 352 of the ring assembly 350 supports the cut ring 378therein and guides the annular knife 30 into the cut ring 378 to preventpartial or offset cutting of the cut ring 378. The ring cup 352 isnested with the backup member 376 by being captured between an innerperipheral surface 372 of the anvil head 340 and the backup member 376.The ring cup 352 generally includes an annular outer wall 360, anannular, first inner wall 362, and a disc-shaped base 364interconnecting the outer wall 360 and the first inner wall 362. Theouter wall 360, the base 364, and the first inner wall 362 cooperativelydefine a cavity or annular chamber 366 dimensioned for receipt of thecut ring 352.

As best shown in FIGS. 24-27 , the outer wall 360 of the ring cup 352has an annular, outer peripheral surface 360 a and an annular, innerperipheral surface 360 b, wherein a thickness of the annular wall 360 isdefined therebetween. An outer lip 368 extends radially outward from theouter peripheral surface 360 a of the outer wall 360. The outer lip 368of the outer wall 360 overlaps the inner race 374 of the anvil head 340to support the ring assembly 350 in the proximal position and resistmovement of the ring assembly 350 toward the distal position.

The outer wall 360 may have a plurality of slits 380 defined therein.The slits are arranged circumferentially about the outer wall 360. Theslits 380 render the outer wall 360 flexible, such that upon distaladvancement of the ring assembly 350 through the recess 370 of the anvilhead 340, the outer wall 360 may flex or bend radially inward to snapinto place under the inner race 374 of the anvil head 340. Inembodiments, instead of or in addition to having the slits 380, theouter wall 360 may be fabricated from a flexible material to facilitateradial contraction of the outer wall 360 during assembly into the anvilhead 340.

The outer wall 360 of the ring cup 352 further includes a chamferedsurface 382 that slopes downwardly (e.g., distally) from a proximal-mostsurface of the outer wall 360. An annular inner edge 384 of thechamfered surface 382 (FIG. 27 ) is disposed radially inward of theinner peripheral surface 360 b of the outer wall 360, such that thechamfered surface 382 defines an undercut or overhang 386. The undercut386 overlays an outer edge 388 of the cut ring 378 to capture the cutring 378 in the annular chamber 366 of the ring cup 352. As such, as theannular knife 30 advances, the chamfered surface 382 guides or redirectsthe knife 30 inwardly and into contact with the cut ring 378 at alocation radially inward of the outer edge 388 of the cut ring 378. Thiseliminates the possibility of a line-to-line stapling condition.

It is contemplated that the location at which the knife 30 contacts thecut ring 378 may be adjusted by adjusting the depth of the undercut 386.For example, to ensure that the knife 30 contacts the cut ring 378 at amore radially inward location, the depth of the undercut 386 in theouter wall 360 may be increased. In addition or in the alternative toincreasing the depth of the undercut 386, the annular inner edge 384 ofthe chamfered surface 382 may extend a greater distance radially inwardrelative to the inner peripheral surface 360 b of the outer wall 360 tocause the knife 30 to contact the cut ring 378 at a more radially inwardlocation.

The ring cup 352 further includes an annular, second inner wall 390disposed radially inward of the first inner wall 362. The second innerwall 390 may be coupled to the first inner wall 362 via a plurality ofbridge members 392 that permit the second inner wall 390 to flexrelative to the first inner wall 362. The second inner wall 390 may alsoinclude a plurality of slits 395 defined therein. The slits 395 arearranged circumferentially about the second inner wall 390 to furtherfacilitate flexing of the second inner wall 390. To assemble the ringcup 352 to the backup member 376, the second inner wall 390 of the ringcup 352 is flexed radially inward and captured under the lip 358 of thebackup member 376.

The cut ring 378 of the ring assembly 350 is received in the annularchamber 366 of the ring cup 352 between the outer wall 360 of the ringcup 352 and the first inner wall 362 of the ring cup 352. The outer edge388 of the cut ring 378 is disposed under the undercut 386 of thechamfered surface 382 of the ring cup 352. It is contemplated that thecut ring 378 may be press fit onto the ring cup 352. Thus, movement ofthe ring cup 352 between proximal and distal positions causescorresponding movement of the cut ring 378. In embodiments, the cut ring378 may be formed through a molding process, e.g., an injection moldingprocess, and extend through a plurality of holes 397 (FIG. 26 ) definedthrough the base portion 364 of the ring cup 352.

The cut ring 378 may be fabricated from a material having a durometerwhich permits the annular knife 30 to pierce through the cut ring 378and bottom out against the base portion 364 of the ring cup 352. Assuch, all of the ring cup 352 or select portions thereof (e.g., thechamfered surface 382 and the base portion 364) is fabricated from aharder material than the cut ring 378. Suitable materials for the cutring 378 include polytetrafluoroethylene, polypropylene or polyester.Other materials are contemplated.

In operation, prior to firing a circular stapling instrument having thesurgical anvil assembly 326 of the presently described embodiment, thering assembly 350 including the backup member 376, the ring cup 352, andthe cut ring 378, is in its retracted or proximal position, as shown inFIG. 28 . The outer lip 368 of the outer wall 360 of the ring cup 352overlaps the inner race 374 of the anvil head 340 to support the ringassembly 350 in the proximal position. With the ring assembly 350 in theproximal position, the inwardly extending fingers 398 of the backupmember 376 are engaged by the anvil center rod to maintain the anvilhead 340 in the first, operative condition, as described above.

Upon actuation of the stapling instrument, the annular knife 30 isadvanced into engagement with the cut ring 378 of the ring assembly 350.In some instances, a section of the annular knife 30 may be out ofvertical registration with the cut ring 378 (e.g., disposed radiallyoutward). In these instances, as the knife 30 is advanced, the knife 30engages the chamfered surface 382 of the ring cup 352, which directs theknife 30 radially inward into vertical registration with the cut ring378. Due to the chamfered surface 382 of the ring cup 352 hanging overthe cut ring 378, the knife 30 makes contact with the cut ring 378radially inward of the outer edge 388 of the cut ring 378.

As advancement of the knife 30 is continued, the knife 30 pierces thecut ring 378 and ultimately engages the base portion 364 of the ring cup352, as shown in FIG. 29 . The force applied by the knife 30 flexes orbends the outer wall 360 of the ring cup 352 inwardly to pass over theinner race 374 of the anvil head 340. The ring cup 352, along with thecut ring 378 and the backup member 376, is then driven distally towardthe distal position.

As the ring assembly 350 is advanced toward the distal position, theinwardly extending fingers 398 of the backup member 378 disengage theanvil center rod, allowing for the anvil head 340 to pivot relative tothe anvil center rod. It is contemplated that the anvil head 340 may beconfigured to pivot automatically relative to the anvil center rod inany manner described herein. In embodiments, the anvil head 340 may bepivoted via any suitable pivoting mechanism, whether it is automatic ormanual.

With reference to FIGS. 30-32 , another embodiment of a surgical anvilassembly 426 is illustrated, similar to the anvil assemblies describedabove. Due to the similarities between the anvil assembly 426 of thepresent embodiment and the anvil assemblies described above, only thoseelements of the anvil assembly 426 deemed necessary to elucidate thedifferences from anvil assemblies described above will be described indetail.

The anvil assembly 426 generally includes an anvil center rod (notshown), similar to the anvil center rods described above, an anvil head440 pivotally mounted to the anvil center rod, and a ring assembly 450configured to selectively unlock the anvil head 440 from the anvilcenter rod. The anvil head 440 is configured to pivot relative to theanvil center rod between a first operative condition and a secondpivoted or tilted condition. The anvil head 440 defines a recess 470therein for receipt of the ring assembly 450. The anvil head 440includes an annular, inner peripheral surface 472 that partially definesthe recess 470.

The anvil head 440 may include a frangible retainer member (not shown),similar to the retainer member 127 described in U.S. Pat. No. 9,532,781,the entire contents of which having been incorporated by referenceabove. The frangible retainer member may be disposed in the recess 470of the anvil head 440 between the inner peripheral surface 472 of theanvil head 440 and the ring assembly 450 so that upon application of athreshold distal force on the ring assembly 450, the frangible retainercollapses, allowing distal advancement of the ring assembly 450 and theannular knife 30.

The ring assembly 440 is received within the recess 470 defined in theanvil head 440 and generally includes a backup member 476, a first cutring 452 nested in the backup member 476, and a second cut ring 478nested in the first cut ring 452. The ring assembly 450 is moved withinthe recess 470 of the anvil head 440 upon application of a forcethereto, e.g., during advancement of the annular knife 30.

The backup member 476 defines a central opening 494 for reception of apost 456 of the anvil head 440. The central opening 494 is dimensionedto facilitate movement of the backup member 476 about the post 456 froma pre-fired, retracted or first position to a post-fired, advanced orsecond position within the recess 470 of the anvil head 440. The backupmember 476, similar to the backup members described above, includes apair of diametrically opposed fingers (not explicitly shown) extendinginwardly into the central opening 494. The fingers are engaged by theanvil center rod to prevent the backup member 476 from moving in aproximal direction and to maintain the anvil head 440 in the operativecondition (e.g., untilted). Pivotal movement of the anvil head 440relative to the anvil center rod is permitted only after the fingers ofthe backup member 476 are distally spaced from the anvil center rod, asalready described above.

The backup member 476 further includes an annular wall or ring 454 and adisc-shaped platform 457 extending radially outward from a distalportion of the annular wall 454. The annular wall 454 has a lip 458extending radially inward from a proximal portion thereof. The lip 458is configured to engage (e.g., via snap-fit engagement) the first cutring 452 to retain the first cut ring 452 with the backup member 476.The backup member 476 may be formed from a hard material such as metal,although other materials of construction are envisioned.

The first cut ring 452 of the ring assembly 450 supports the second cutring 476 therein and provides a surface on which staples are to be cut.The first cut ring 452 is fabricated from a first material, such as, forexample, a hard plastic, that resists being pierced by the annular knife30. The first cut ring 452 is nested with the backup member 476 by beingcaptured between the inner peripheral surface 472 of the anvil head 440and the backup member 476. The first cut ring 452 includes a proximalportion 452 a, a distal portion 452 b, and an annular cutout or recess452 c disposed therebetween. The annular recess 452 c is defined in anouter peripheral surface 460 of the first cut ring 452 and captures thesecond cut ring 478 therein.

The first cut ring 452 further defines an annular groove 462 in theproximal portion 452 a thereof that extends circumferentially along aproximal surface 464 of the first cut ring 452. While the groove 462 isillustrated as having a V-shaped configuration, it is contemplated thatthe groove 462 may assume any suitable configuration, such as, forexample, U-shaped or squared. The groove 462 is in vertical registrationwith the annular recess 452 c of the first cut ring 452 and isconfigured to guide the annular knife 30 (FIG. 32 ) radially inwardtoward an apex 466 of the groove 462.

The proximal portion 452 a of the first cut ring 452 has a reducedthickness defined between the apex 466 of the groove 462 and the annularrecess 452 c. As such, when the annular knife 30 is advanced distallyinto the proximal portion 452 a of the first cut ring 452, the annularknife 30 cuts through the proximal portion 452 a of the first cut ring452 along a vertical pathway “P” running through the groove 462 of thefirst cut ring 452. The depth of the groove 462 may be increased toincrease the force necessary for the annular knife 30 to cuttherethrough, or decreased to decrease the force necessary for theannular knife 30 to cut therethrough.

The second cut ring 478 of the ring assembly 450 is received in theannular recess 452 c of the first cut ring 452. As mentioned above, thesecond cut ring 478 is in vertical registration with the groove 462 ofthe first cut ring 452, such that the groove 462 of the first cut ring452 guides the annular knife 30 into the second cut ring 478 at alocation radially inward of an outer peripheral surface of the secondcut ring 478. It is contemplated that the second cut ring 478 may bepress fit into the annular recess 452 c of the first cut ring 452. Thus,movement of the first cut ring 452 between proximal and distal positionscauses corresponding movement of the second cut ring 478. The relativelyharder first cut ring 452 provides a surface on which the annular knife30 can cut through staples without being dragged into the relativelysofter second cut ring 478, which is used to cut tissue cleanly.

In embodiments, the second cut ring 478 may be formed through a moldingprocess, e.g., an injection molding process. The second cut ring 478 maybe fabricated from a material having a durometer which permits theannular knife 30 to pierce through the second cut ring 478 and bottomout against the distal portion 452 b of the first cut ring 452 b. Assuch, the second cut ring 478 is fabricated from a softer material thanthe first cut ring 452. Suitable materials for the second cut ring 478include polytetrafluoroethylene, polypropylene or polyester. Othermaterials are contemplated.

In operation, prior to firing a circular stapling instrument having thesurgical anvil assembly 426 of the presently described embodiment, thering assembly 450, including the backup member 476, the first cut ring452, and the second cut ring 478, is in its retracted or proximalposition. The frangible retainer member (not explicitly shown) isinterposed between the backup member 476 and the inner surface 472 ofthe anvil head 440 to support the ring assembly 450 in the proximalposition. With the ring assembly 450 in the proximal position, theinwardly extending fingers of the backup member 476 are engaged by theanvil center rod, such that the anvil head 440 is retained in the first,operative condition.

Upon actuation of the stapling instrument, the annular knife 30 isadvanced into engagement with ramped surfaces 462 a, 462 b (FIG. 31 )that define the groove 462 of the first cut ring 452. The rampedsurfaces 462 a, 462 b direct the knife 30 radially inward into verticalregistration with a central portion of the second cut ring 478. Theannular knife 30 moves through the groove 462 and contacts the apex 466of the groove 462, transferring the distally-oriented force to thefrangible retainer member. Upon applying a threshold force on thefrangible retainer member, the frangible retainer member collapses,allowing for distal movement of the ring assembly 450 through the recess470 of the anvil head 440.

As the ring assembly 450 is advanced toward the distal position, theinwardly extending fingers of the backup member 476 disengage from theanvil center rod, allowing for the anvil head 440 to pivot relative tothe anvil center rod. It is contemplated that the anvil head 440 may beconfigured to pivot automatically relative to the anvil center rod inany manner described herein. In embodiments, the anvil head 440 may bepivoted via any suitable pivoting mechanism, whether it is automatic ormanual.

As advancement of the annular knife 30 is continued, the annular knife30 cuts through the proximal portion 452 a of the first cut ring 452,slicing through any tissue and staples along its pathway and disseveringan outer circumferential section of the proximal portion 452 a of thefirst cut ring 452 from the remainder of the proximal portion 452 a ofthe first cut ring 452. It is contemplated that the outercircumferential section of the first cut ring 452 remains adhered, viafriction, to an outer surface of the annular knife 30. As advancement ofthe annular knife 30 is continued, the annular knife 30 cuts through thesecond cut ring 478 and ultimately bottoms out on the distal portion 452b of the first cut ring 452. In embodiments, the frangible retainermember may be configured to collapse after the annular knife 30 cutsthrough the proximal portion 452 a of the first cut ring 452 rather thanbefore.

With reference to FIGS. 33-40 , another embodiment of a surgical anvilassembly 526 is illustrated, similar to the anvil assemblies describedabove. Due to the similarities between the anvil assembly 526 of thepresent embodiment and the anvil assemblies described above, only thoseelements of the anvil assembly 526 deemed necessary to elucidate thedifferences from the above anvil assemblies will be described in detail.

With reference to FIGS. 33 and 34 , the anvil assembly 526 generallyincludes an anvil center rod (not shown), similar to the anvil centerrods described above, an anvil head 540 pivotally mounted to the anvilcenter rod, and a ring assembly 550 configured to selectively unlock theanvil head 540 from the anvil center rod. The anvil head 540 isconfigured to pivot relative to the anvil center rod between a firstoperative condition and a second pivoted or tilted condition.

The anvil head 540 defines a recess 570 therein dimensioned for receiptof the ring assembly 550. The anvil head 540 includes a post 556centrally located within the recess 570 and projects proximally from afloor of the recess 570. The post 556 pivotally couples the anvil head540 to the anvil center rod. For example, the post 556 of the anvil head540 may be pivotally coupled to a pair of distal spaced arms of theanvil center rod. The post 556 has a body 522 having an annular ledge524 projecting radially outward therefrom. The annular ledge 524 isconfigured to selectively maintain the ring assembly 550 in a pre-fired,proximal position. The body 522 of the post 556 defines an annulardepression 526 disposed underneath or distally of the annular ledge 524.

The ring assembly 550 is received within the recess 570 defined in theanvil head 540 and generally includes a snap collar 552 engaged to thebody 522 of the post 556, a backup member 576 supported on the snapcollar 552, and a cut ring 578 captured between the snap collar 552 andthe backup member 576. The ring assembly 550 is moved within the recess570 upon application of a force thereto, e.g., during advancement of anannular knife, such as, for example, annular knife 30 (FIGS. 3 and 6 ).

With specific reference to FIGS. 35-37 , the snap collar 552 of the ringassembly 550 is configured to selectively maintain the ring assembly 550in the proximal position, but allow for movement of the ring assembly550 toward the distal position upon the application of adistally-oriented threshold force thereon. The snap collar 552 may be amonolithically formed piece of plastic or may be constructed from aplurality of connected components. The snap collar 552 includes aplurality of horizontally-extending support surfaces or flanges 554, anda plurality of vertical extensions 558 interposed between respectiveadjacent pairs of the flanges 554. As such, the flanges 554 and verticalextensions 558 are alternately arranged around the circumference of thesnap collar 552. The snap collar 552 may include four flanges 554arranged circumferentially about the snap collar 552 in 90° spacedrelation to one another. Similarly, the snap collar 552 may include fourvertical extensions 558 arranged circumferentially about the snap collar552 in 90° spaced relation to one another. It is contemplated that thesnap collar 552 may have more or less than four flanges 554 and verticalextensions 558.

The flanges 554 of the snap collar 552 may be planar and support thebackup member 576 thereon (FIG. 36 ), such that distal movement of thebackup member 576 causes distal movement of the snap collar 552. Thevertical extensions 558 of the snap collar 552 may extend proximally, ata perpendicular angle, relative to the flanges 554. The verticalextensions 558 each include an annular inner lip 560 extending radiallyinward therefrom, and an annular outer lip 562 extending radiallyoutward therefrom. The annular inner lips 560 are supported on theannular ledge 524 of the post 556 of the anvil head 540 when the ringassembly 550 is in the proximal position. The annular inner lips 560 ofthe snap collar 552 resist movement of the ring assembly 550 toward thedistal position until the distally-oriented threshold force causesoutward flexure of the vertical extensions 558, which disengages theannular inner lips 560 of the snap collar 552 from the annular ledge 524of the post 556 of the anvil head 540. The annular outer lips 562 of thesnap collar 552 overlay a proximal surface of the cut ring 578 toprevent the cut ring 578 from moving relative to the snap collar 552.

With reference to FIGS. 35, 36, 38A, and 38B, the backup member 576includes a ring body 580 defining a central opening 594, a pair ofdiametrically opposed tabs 582 extending radially inward from theannular body 594 into the central opening 594, and a pair ofdiametrically opposed fingers 598 extending inwardly into the centralopening 594. The central opening 594 receives the post 556 of the anvilhead 540 and is dimensioned to facilitate movement of the backup member576 about the post 556 from a pre-fired, retracted or first position toa post-fired, advanced or second position within the recess 570 of theanvil head 540. The backup member 576 is retained in the proximalposition via the snap collar's 552 engagement with the annular ledge 524of the post 556.

The tabs 582 of the backup member 576 are supported on a first pair ofdiametrically opposed flanges 554 of the snap collar 552. The tabs 582of the backup member 576 are configured to transfer a distally-orientedforce, applied by an advancement of the annular knife 30, to the snapcollar 552. The fingers 598 of the backup member 576 extend radiallyinward from the ring body 580 a further extent than do the tabs 582 ofthe backup member 576 and are received in cutouts 528 in the body 522 ofthe post 556. The fingers 598 of the backup member 576 have a firstportion 598 a extending horizontally from the ring body 580 of thebackup member 576, and a second portion 598 b extending verticallyupward or proximal from the first portion 598 a. The first portion 598 aof each of the fingers 598 is supported on a second pair ofdiametrically opposed flanges 554 of the snap collar 552.

The second portion 598 b of the fingers 598 are engaged by the anvilcenter rod to prevent the backup member 576 from moving in a proximaldirection and to maintain the anvil head 540 in the operative condition(e.g., untilted). Pivotal movement of the anvil head 540 relative to theanvil center rod is permitted only after the fingers 598 of the backupmember 576 are distally spaced from the anvil center rod. The backupmember 576 may be stamped from a hard material such as metal, althoughother materials of construction are envisioned.

With reference to FIGS. 33, 35, 36, 39, and 40 , the cut ring 578 of thering assembly 550 is supported on the backup member 576 and has an innerperipheral surface 590 that is captured between the annular outer lip562 of the snap collar 552 and the tabs 582 and fingers 598 of thebackup member 576. Accordingly, proximal or distal movement of thebackup member 576 results in a corresponding proximal or distal movementof the snap collar 552 and the cut ring 578. The cut ring 578 has aplurality of surface features 596 protruding from an outer peripheralsurface thereof. The surface features 596 are press fit under an innerrace 574 of the anvil head 540 to retain the ring assembly 550 in therecess 570.

The cut ring 578 may be fabricated from a material having a durometerwhich permits the annular knife 30 to pierce through the cut ring 578and bottom out against the ring body 580 of the backup member 576. Assuch, the backup member 576 may be fabricated from a harder materialthan the cut ring 578. Suitable materials for the cut ring 578 includepolytetrafluoroethylene, polypropylene or polyester. Other materials arecontemplated.

In operation, prior to firing of a circular stapling instrument havingthe surgical anvil assembly 526 of the presently described embodiment,the ring assembly 550, including the backup member 576, the snap collar552, and the cut ring 578, is in its retracted or proximal position inthe recess 570 of the anvil head 540, as shown in FIG. 39 . The annularinner lips 560 of the snap collar 552 are supported on the annular ledge524 of the post 556 of the anvil head 540, and the surface features 596of the cut ring 578 are supported on the inner race 574 of the anvilhead 540. With the ring assembly 550 in the proximal position, theinwardly extending fingers 598 of the backup member 576 are engaged bythe anvil center rod, such that the anvil head 540 is retained in thefirst, operative condition.

Upon actuation of the stapling instrument, the annular knife is advancedinto engagement with the cut ring 578 of the ring assembly 550, whichtransfers the distally-oriented force to the backup member 576, which inturn transfers the distally-oriented force to the snap collar 552. Uponachieving a threshold force, the vertical extensions 558 of the snapcollar 552 flex outwardly to separate the annular inner lips 560 of thesnap collar 552 from the annular ledge 524 of the post 556 of the anvilhead 540.

With the annular inner lips 560 of the snap collar 552 out ofoverlapping engagement with the annular ledge 524 of the post 556 of theanvil head 540, the distally-oriented force imparted by the annularknife drives the ring assembly 550 distally, whereby the backup member576 contacts the inner surface 572 of the anvil head 540, and theannular inner lips 560 of the snap ring 552 are received in thedepression 526 of the post 556 of the anvil head 540, as shown in FIG.40 . Continued advancement of the annular knife causes the annular knifeto pierce the cut ring 578 and ultimately bottom out against the ringbody 580 of the backup member 576.

In embodiments, the cut ring 578 and the snap collar 552 may beconfigured such that the annular knife cuts through the cut ring 578prior to moving the snap collar 552 out of engagement with the annularledge 524 of the post 556 of the anvil head 554.

As the ring assembly 550 is advanced toward the distal position, theinwardly extending fingers 598 of the backup member 576 disengage fromthe arms of the anvil center rod, allowing for the anvil head 540 topivot relative to the anvil center rod. It is contemplated that theanvil head 540 may be configured to pivot automatically relative to theanvil center rod in any manner described herein. In embodiments, theanvil head 540 may be pivoted via any suitable pivoting mechanism,whether it is automatic or manual.

With reference to FIGS. 41-44 , another embodiment of a surgical anvilassembly 626 is illustrated, similar to the anvil assemblies describedabove. Due to the similarities between the anvil assembly 626 of thepresent embodiment and the anvil assemblies described above, only thoseelements of the anvil assembly 626 deemed necessary to elucidate thedifferences from the above anvil assemblies will be described in detail.

The anvil assembly 626 includes an anvil center rod 638 and an anvilhead 640 pivotally mounted to the anvil center rod 638. The anvil head640 is adapted to pivot between a first operative condition depicted inFIG. 41 and a second pivoted or tilted condition depicted in FIG. 44 .The anvil head 640 includes a housing 654 having a post 656 and an anviltissue contact surface 658. The post 656 may include a pair of spacedpost arms defining transverse bores 664 extending through the spacedpost arms. The anvil center rod 638 is at least partially positionedabout the post 656 and coupled to the anvil head 640 through a pivotmember 666.

The anvil center rod 638 may include a pair of distal spaced arms 642defining a pair of diametrically opposed, longitudinally-extending slots662. The distal spaced arms 642 includes a distal end through whichtransverse bores 644 are defined for receiving the pivot member 666 thatpivotally couples the post 656 of the anvil head 640 to the distalspaced arms 642 of the anvil center rod 638. The pivot member 666 iscoupled to a first location “L1” of the post 656 of the anvil head 640and which is aligned with a central longitudinal axis “X” defined by theanvil center rod 638.

The anvil assembly 626 further includes a pivoting assembly 600, whichreplaces the conventional plunger and cam latch assembly for driving thetilting of the anvil head 640. The pivoting assembly 600 is at leastpartially received within the anvil center rod 638, e.g., between thespaced arms 642, and is spring biased in a proximal direction by abiasing member 602, such as, for example, a coil spring. The pivotingassembly 600 includes a linkage arm 604 received in one of the slots 662of the distal spaced arms 642 of the anvil center rod 638. The linkagearm 604 has an L-shaped configuration and includes an elongated shaft606 and a foot or flange 608 extending perpendicularly from a proximalend 606 a of the shaft 606. In embodiments, the linkage arm 604 mayassume any suitable shape, such as, for example, linear, curved, or thelike. The foot 608 of the linkage arm 604 has a detent or post 610extending distally therefrom for supporting the biasing member 602 ofthe pivoting assembly 600.

The shaft 606 of the linkage arm 604 is disposed off-center from thecentral longitudinal axis “X” of the anvil center rod 638. The shaft 606has a distal end 606 b pivotally coupled to a second location “L2” ofthe post 656 of the anvil head 640 via a pivot member 612, such as, forexample, a pin. The second location “L2” of the post 656 of the anvilhead 640 at which the shaft 606 is pivotally coupled is both distal andlaterally offset from the first location “L1” at which the anvil centerrod 638 is pivotally coupled to the post 656 of the anvil head 640. Assuch, a longitudinal translation of the shaft 606 in the proximal ordistal direction effects a pivoting of the anvil head 640 about thefirst location “L1” in a counter-clockwise or clockwise direction,respectively.

The biasing member 602 of the pivoting assembly 600 is disposed withinthe anvil center rod 638 and in alignment with the central longitudinalaxis “X” of the anvil center rod 638 and the first location “L1.” Thebiasing member 602 defines a bore 614 therethrough that receives thedetent 610 of the foot 608 of the linkage arm 604 to support the biasingmember 602. The biasing member 602 is interposed between the foot 608 ofthe linkage arm 604 and the post 656 of the anvil head 640 while beingin a compressed state. As such, the compressed biasing member 602 exertsa proximally-oriented force on the foot 608 of the linkage arm 604,which is transferred to the second location “L2” of the post 656 of theanvil head 640. Accordingly, upon unlocking the anvil head 640 from theanvil center rod 638, the biasing member 602 drives or pulls the anvilhead 640 toward the second, tilted condition, as will be described.

The anvil assembly 626 may further include a backup member (not shown)and a cut ring (not shown), similar to the backup members and cut ringsdescribed above. The backup member is moved within a recess 670 definedin the housing 658 of the anvil head 640 upon application of a forcethereto, e.g., during advancement of an annular knife 30 (FIGS. 3 and 6).

In operation, prior to firing of a circular stapling instrument havingthe surgical anvil assembly 626 of the presently described embodiment,the backup member is in its retracted or proximal position in the recess670 of the anvil head 640. With the backup member in the proximalposition, the backup member is engaged by the spaced arms 642 of theanvil center rod 638, such that the anvil head 640 is retained in thefirst, operative condition and prevented from pivoting despite theproximally-oriented force exerted by the biasing member 602 on the anvilhead 640 via the linkage arm 604.

Upon actuation of the stapling instrument, the annular knife is advancedinto engagement with the cut ring, which transfers the distally-orientedforce to the backup member, as described in previous embodiments. As thebackup member is advanced toward the distal position, the backup memberdisengages from the arms 642 of the anvil center rod 638, unlocking theanvil head 640 from the anvil center rod 638. With the anvil head 640unlocked from the anvil center rod 638, e.g., the anvil head 640 is freeto pivot, the biasing member 602 of the pivoting assembly 600 drives thelinkage arm 604 in a proximal direction, whereby the linkage arm 604pivots the anvil head 640 relative to the anvil center rod 638 in thecounter-clockwise direction, indicated by arrow “B” in FIG. 44 . Afterthe anvil head 640 pivots to the second, tilted condition, the anvilhead 640 covers the linkage arm 604, preventing the linkage arm 604 fromgetting caught on tissue during removal of the surgical anvil assembly626 from a surgical site.

During some operations, the anvil head 640 may be manually pivoted backto the first, operative condition against the spring bias of the biasingmember 602. In such instances, as the anvil head 640 is pivoted back tothe first, operative condition, the linkage arm 604 is driven or pulledin a distal direction and the biasing member 602 is compressed betweenthe foot 608 of the linkage arm 604 and the post 656 of the anvil head640, resetting the pivoting assembly 600.

With reference to FIGS. 45-48 , another embodiment of a surgical anvilassembly 726 is illustrated, similar to the anvil assemblies describedabove. Due to the similarities between the anvil assembly 726 of thepresent embodiment and the anvil assemblies described above, only thoseelements of the anvil assembly 726 deemed necessary to elucidate thedifferences from the above anvil assemblies will be described in detail.

The anvil assembly 726 includes an anvil center rod 738 and an anvilhead 740 pivotally mounted to the anvil center rod 738. The anvil head740 is adapted to pivot between a first, operative condition and asecond, pivoted or tilted condition. The anvil center rod 738 mayinclude a pair of distal spaced arms 742 for capturing a 756 post of theanvil head 740 therebetween. The distal spaced arms 742 of the anvilcenter rod 738 defines transverse bores 744 therethrough for receiving apivot member 766, as will be described.

The anvil head 740 includes a housing 754 defining a recess 770 thereinand the post 756 is centrally disposed within the recess 770 and extendsproximally therefrom. The post 756 includes a pair of spaced post arms760 defining a slot 762 dimensioned to capture a cam latch 750 therein.The spaced post arms 760 define transverse bores 764 therethroughdimensioned for receipt of the pivot member 766. The anvil center rod738 is at least partially positioned about the post 756 and coupled tothe anvil head 740 through the pivot member 766 which extends throughrespective transverse bores 744, 764 of the distal spaced arms 742 ofthe anvil center rod 738 and the spaced post arms 760 of the post 756 topivotally couple the anvil head 740 to the anvil center rod 738.

With reference to FIGS. 45 and 46 , the cam latch 750 is received withinthe slot 762 defined between the spaced post arms 760 of the post 756and coupled to the anvil center rod 738 and the post 756 via the pivotmember 766. The cam latch 750 defines a bore or pin opening 752 throughwhich the pivot member 766 extends. The pin opening 752 in the cam latch750 is defined by an annular inner surface 753 of the cam latch 750. Thecam latch 750 has a proximally-located edge 757 engaged to a plunger 746for driving a rotation of the cam latch 750. The cam latch 750 isrotationally fixed within the slot 762 of the post 756 of the anvil head740, such that as the cam latch 750 rotates, due to a spring bias of theplunger 746, the anvil head 740 rotates with the cam latch 750 relativeto the anvil center rod 738.

As briefly mentioned above, the pivot member 766 extends through thetransverse bores 744 of the distal spaced arms 742 of the anvil centerrod 738, the transverse bores 764 of the spaced post arms 760 of thepost 756, and the pin opening 752 of the cam latch 750 to allow forpivoting or rotation of the anvil head 740 relative to the anvil centerrod 738. The pivot member 766 extends through the bores 744, 764 and thepin opening 752 in a slip fit manner to ease assembly.

The pivot member 766 is an elongated pin-like structure having opposingfirst and second ends 766 a, 766 b and an intermediate portion 766 cdisposed therebetween. It is contemplated that the first and second ends766 a, 766 b and the intermediate portion 766 c of the pivot member 766may be monolithically formed. An annular groove 780 is formed in anouter surface 782 of the pivot member 766. The annular groove 780 isdisposed along the intermediate portion 766 c of the pivot member 766.Accordingly, the first and second ends 766 a, 766 b of the pivot member766 have a first diameter, and the intermediate portion 766 c of thepivot member 766 has a second diameter, less than the first diameter.

The groove 780 in the pivot member 766 may be cylindrical and extendcircumferentially about the intermediate portion 766 c of the pivotmember 766. As such, the groove 780 has stepped portions 784 a, 784 b onopposite sides thereof to limit lateral movement of the pivot member 766within and relative to the pin opening 752 of the cam latch 750. Thediameter of the intermediate portion 766 c is less than the diameter ofthe pin opening 752 of the cam latch 750. This allows for a simplifiedslip fit of the pivot member 766 into the pin opening 752 of the camlatch 750 during assembly.

With reference to FIGS. 45-48 , the inner surface 753 of the cam latch750 has a proximal portion 755 that is received in the groove 780 of thepivot member 766 and which is spring biased into contact with the outersurface 782 of the pivot member 766 via the plunger 746, as will bedescribed. The length of the groove 780 is greater than the thickness ofthe cam latch 750 to allow for some lateral movement of the pivot member766 within the pin opening 752 of the cam latch 750.

The anvil assembly 726 further includes the plunger 746 and a plungerspring 748. The plunger 746 is at least partially received within theanvil center rod 738, e.g., between the spaced arms 742, and is springbiased in a distal direction by the plunger spring 748. The plunger 746includes a plunger finger 759 engaged to the proximal edge 757 of thecam latch 50 to maintain the proximal portion 755 of the inner surface653 of the cam latch 750 in the groove 780 of the pivot member 766. Dueto the spring bias of the plunger 746 on the cam latch 750, the proximalportion 755 of the inner surface 753 of the cam latch 750 isfrictionally engaged with the outer surface 782 of the pivot member 766to retain the pivot member 766 in the pin opening 752 of the cam latch750.

The anvil assembly 726 further includes a backup member 776 and a cutring 778, similar to the backup members and cut rings described above.The backup member 776 is moved within the recess 770 of the anvil head740 upon application of a force thereto, e.g., during advancement of anannular knife 30 (FIGS. 3 and 6 ). The backup member 776 includes a pairof diametrically opposed fingers (not explicitly shown) extendinginwardly. The fingers are engaged by the spaced arms 742 of the anvilcenter rod 738 to prevent the backup member 776 from moving in aproximal direction and to maintain the anvil head 740 in the operativecondition (e.g., untilted). Pivotal movement of the anvil head 740relative to the anvil assembly 726 is permitted only after the fingers798 are distally spaced from the arms 742 of the anvil center rod 738,as described in the previous embodiments.

In operation, prior to firing of a circular stapling instrument havingthe surgical anvil assembly 726 of the presently described embodiment,the backup member 676 is in its retracted or proximal position in the770 recess of the anvil head 740. With the backup member 776 in theproximal position, the inwardly extending fingers of the backup member776 are engaged by the spaced arms 742 of the anvil center rod 738, suchthat the anvil head 740 is retained in the first, operative conditionand prevented from pivoting despite the distally-oriented force exertedby the plunger 746 on the anvil head 740 via the cam latch 750.

Upon actuation of the stapling instrument, the annular knife 30 isadvanced into engagement with the cut ring 778, which transfers thedistally-oriented force to the backup member 776. As the backup member776 is advanced toward the distal position, the inwardly extendingfingers of the backup member 776 disengage from the arms 742 of theanvil center rod 738, unlocking the anvil head 740 from the anvil centerrod 738. With the anvil head 740 unlocked from the anvil center rod 738(e.g., the anvil head 740 is free to pivot), the spring biased plunger746 drives a rotation of the cam latch 750 about the pivot member 766.Due to the cam latch 750 being rotationally fixed within the anvil head740, the anvil head 740 is caused to rotate relative to the anvil centerrod 738 about the pivot member 766. In embodiments, the pivot member 766may rotate with the anvil head 740.

With reference to FIGS. 49-52 , another embodiment of a surgical anvilassembly 826 is illustrated, similar to the anvil assemblies describedabove. Due to the similarities between the anvil assembly 826 of thepresent embodiment and the anvil assemblies described above, only thoseelements of the anvil assembly 826 deemed necessary to elucidate thedifferences from the anvil assemblies above will be described in detail.

The anvil assembly 826 includes an anvil center rod 838 and an anvilhead 840 pivotally mounted to the anvil center rod 838. The anvil head840 is adapted to pivot between a first, operative condition and asecond, pivoted or tilted condition (FIGS. 49 and 52 ). The anvil centerrod 838 may include a pair of distal spaced arms 842 for capturing apost 856 of the anvil head 840 therebetween. The distal spaced arms 842of the anvil center rod 838 define transverse bores therethrough forreceiving a pivot member 866.

The anvil head 840 defines a recess 870 therein. The post 856 iscentrally disposed within the recess 870 and extends proximallytherefrom. The post 856 includes a pair of spaced post arms 860 defininga slot 862 dimensioned to capture a cam latch 850 therein. The spacedpost arms 860 define transverse bores 864 therethrough dimensioned forreceipt of the pivot member 866. The anvil center rod 838 is at leastpartially positioned about the post 856 and coupled to the anvil head840 through the pivot member 866 which extends through respectivetransverse bores of the distal spaced arms 842 of the anvil center rod838 and the spaced post arms 860 of the post 856 to pivotally couple theanvil head 840 to the anvil center rod 838. The post 856 furtherincludes a pair of flanges 880 projecting proximally from the respectivepair of post arms 860. The flanges 880 each have a vertical surface 882projecting perpendicularly from a rounded surface 884 of the respectivepost arms 860.

The cam latch 850 is received between the spaced post arms 860 of thepost 856 and between the flanges 880. The cam latch 850 is coupled tothe anvil center rod 838 and the post 856 via the pivot member 866 whichextends through a bore or pin opening 868 of the cam latch 50. As bestshown in FIG. 51 , the cam latch 850 has an outer peripheral surface 852that includes a camming region 852 a and a notched region 852 bcontiguous with the camming region 852 a. The camming region 852 a mayhave an arcuate shape and is configured to be engaged with a plunger 846(FIG. 52 ) that drives a rotation of the cam latch 850.

The notched region 852 b of the cam latch 850 has a profile that matchesa profile cooperatively defined by the vertical surface 882 of theflanges 880 and the rounded surface 884 of the spaced post arms 860. Thenotched region 852 b includes a stop surface 854 that extendssubstantially radially inward from an end of the camming region 852 b.The stop surface 854 is configured to engage a plunger finger 857 of theplunger 846 upon the anvil head 840 entering the second, titledcondition, as shown in FIGS. 49 and 52 . The cam latch 850 isrotationally fixed within the slot 862 of the post 856 of the anvil head840, such that as the cam latch 850 rotates, due to a spring bias of theplunger 846, the anvil head 840 rotates with the cam latch 850 relativeto the anvil center rod 838.

The anvil assembly 826 further includes the plunger 846 and a plungerspring 848. The plunger 846 is at least partially received within theanvil center rod 838, e.g., between the spaced arms 842, and is springbiased in a distal direction by the plunger spring 848. The plungerspring 848 has a spring constant high enough to prevent a manualcompression of the plunger spring 848. As such, manual pivoting of theanvil head 840 from the tilted condition back towards the untiltedcondition is resisted by the plunger spring 848.

The plunger 846 includes the plunger finger 857 at its distal end, whichis engaged to the camming region 852 a of the cam latch 850 to bias thecam latch 850 and, in turn, the anvil head 840, toward the second,tilted condition. When the anvil head 840 is free to pivot relative tothe anvil center rod 838, the plunger finger 857 pushes against thecamming region 852 a of the cam latch 850, whereby the camming region852 a of the cam latch 850 rides along the plunger finger 857, rotatingthe anvil head 840. Upon the anvil head 840 entering the second, tiltedcondition, the notched region 852 b of the cam latch 850 passes over theplunger finger 857, whereby the stop surface 854 of the cam latch 850 ispositioned in contact with the plunger finger 857. Due to the contactbetween the stop surface 854 of the cam latch 850 and the plunger finger857, rotation of the cam latch 850 in the opposite direction (e.g.,rotation of the anvil head 840 back toward the first, operativecondition) is resisted by the plunger 846 and the plunger spring 848.

The anvil assembly 826 further includes a backup member 876 and a cutring 878, similar to the backup members and cut rings described above.The backup member 876 is moved within the recess 870 of the anvil head840 upon application of a force thereto, e.g., during advancement of theannular knife 30 (FIGS. 3 and 6 ). The backup member 876 includes a pairof diametrically opposed fingers 898 extending inwardly. The fingers 898are engaged by the spaced arms 842 of the anvil center rod 838 toprevent the backup member 876 from moving in a proximal direction and tomaintain the anvil head 840 in the operative condition (e.g., untilted).Pivotal movement of the anvil head 840 relative to the anvil assembly826 is permitted only after the fingers 898 are distally spaced from thearms 842 of the anvil center rod 838.

In operation, prior to firing of a circular stapling instrument havingthe surgical anvil assembly 826 of the presently described embodiment,the backup member 876 is in its retracted or proximal position in therecess 870 of the anvil head 840. With the backup member 876 in theproximal position, the inwardly extending fingers 898 of the backupmember 876 are engaged by the spaced arms 842 of the anvil center rod838 such that the anvil head 840 is retained in the first, operativecondition and prevented from pivoting despite the distally-orientedforce exerted by the plunger 846 on the anvil head 840 via the cam latch850.

Upon actuation of the stapling instrument, the annular knife 30 isadvanced into engagement with the cut ring 878, which transfers thedistally-oriented force to the backup member 876. As the backup member876 is advanced toward the distal position, the inwardly extendingfingers 898 of the backup member 876 disengage from the arms 842 of theanvil center rod 838, unlocking the anvil head 840 from the anvil centerrod 838, as described in detail above. With the anvil head 840 unlockedfrom the anvil center rod 838 (e.g., the anvil head 840 is free topivot), the spring biased plunger 846 drives a rotation of the cam latch850. Due to the cam latch 850 being rotationally fixed within the anvilhead 840, the anvil head 840 is caused to rotate relative to the anvilcenter rod 838.

Upon the anvil head 840 rotating to the second, tilted condition, theplunger 846 is received in the notched region 852 b of the cam latch850, whereby the stop surface 854 of the notched region 852 b of the camlatch 850 overlaps with the plunger finger 857. As such, an attempt torotate the anvil head 840 back toward the first, operative conditionwill be resisted by the distally-oriented force exerted on the notchedregion 852 b of the cam latch 850 by the spring biased plunger 846. Asnoted above, the biasing member 848 has a spring constant high enough toresist a manual attempt at resetting the anvil head 840.

With reference to FIGS. 53-55 , another embodiment of a surgical anvilassembly 926 is illustrated, similar to the anvil assemblies describedabove. Due to the similarities between the anvil assembly 926 of thepresent embodiment and the anvil assemblies described above, only thoseelements of the anvil assembly 926 deemed necessary to elucidate thedifferences from anvil assemblies described above will be described indetail.

The anvil assembly 926 generally includes an anvil center rod (notshown), similar to the anvil center rods described above, an anvil head940 pivotally mounted to the anvil center rod, and a ring assembly 950configured to selectively unlock the anvil head 940 from the anvilcenter rod. The anvil head 940 is configured to pivot relative to theanvil center rod between a first operative condition and a secondpivoted or tilted condition.

The anvil head 940 includes an inner surface 972 defining a recess 970therein dimensioned for receipt of the ring assembly 950. The innersurface 972 has an outer periphery 973 that defines an annular groove975 therein. The groove 975 extends radially outward from the recess 970and is in communication therewith. The groove 975 is disposed adjacent atissue contacting surface 958 of the anvil head 940 and extendscircumferentially about the outer periphery 973 of the inner surface 972of the anvil head 940. A height of the groove 975 is defined between aproximal ledge 975 a and a distal ledge 975 b thereof.

The ring assembly 940 includes a backup member 976, similar to backupmember 476 described above, and a cut ring 978. The backup member 976 isreceived in the recess 970 of the anvil head 940, and the cut ring 978is nested in the backup member 976. The cut ring includes an annularinner body portion 978 a and an annular outer body portion 978 bintegrally formed with, and disposed circumferentially about, the innerbody portion 978 a. The inner and outer body portions 978 a, 978 b maybe formed from a unitary piece of polytetrafluoroethylene, polypropyleneor polyester. Other materials are contemplated. In some embodiments, theouter body portion 978 b may be a separate piece attached to the innerbody portion 978 a.

The inner body portion 978 a of the cut ring 978 is supported on thebackup member 976 and is disposed in the recess 970 of the anvil head940, and the outer body portion 978 b of the cut ring 978 is capturedbetween the proximal and distal ledges 975 a, 975 b of the groove 975 ofthe anvil head 940. The cut ring 978 has a greater diameter than thediameter of the recess 970 of the anvil head 940, such that the cut ring978 may be press-fit into the recess 970 during assembly. Onceassembled, the outer body portion 978 b of the cut ring 978 extendsradially beyond the backup member 976. Due to the outer body portion 978b of the cut ring 978 overlapping with the proximal and distal ledges975 a, 975 b, both proximal and distal movement of the outer bodyportion 978 b of the cut ring 978 out of the groove 975 is resisted. Theouter body portion 978 b of the cut ring 978 may have a reducedthickness in relation to the inner body portion 978 a to allow for someplay of the outer body portion 978 b of the cut ring 978 within thegroove 975, as will be described. In embodiments, the height of theinner body portion 978 a of the cut ring 978 may be substantiallysimilar to or the same as the height of the groove 975.

In operation, prior to firing a circular stapling instrument having thesurgical anvil assembly 926 of the presently described embodiment, thering assembly 950, including the backup member 976 and the cut ring 978,is in its retracted or proximal position. A frangible retainer member(not explicitly shown) is interposed between the backup member 976 andthe inner surface 972 of the anvil head 940 to support the ring assembly950 in the proximal position, as shown in FIG. 53 . With the ringassembly 950 in the proximal position, the backup member 976 is engagedby the anvil center rod, such that the anvil head 940 is retained in thefirst, operative condition.

Upon actuation of the stapling instrument, an annular knife, such as,for example, the annular knife 30 shown in FIG. 6 , is advanced intoengagement with the cut ring 978 and dissevers or shears off the outerbody portion 978 b of the cut ring 978 from the inner body portion 978 aof the cut ring 978. Upon cutting through the cut ring 978, the annularknife 30 engages the backup member 976, thereby driving the backupmember 976 toward the distal position.

Due to the inner body portion 978 a of the cut ring 978 being retainedwith the backup member 976, the inner body portion 978 a moves towardthe distal position with the backup member 976. The outer body portion978 b of the cut ring 978 is captured between the outer periphery 973 ofthe inner surface 972 of the anvil head 940 and an outer surface of theannular knife 30. Thus, as shown in FIG. 54 , the outer body portion 978b of the cut ring 978 is held in the groove 975 as the inner bodyportion 978 a of the cut ring 978 is distally advanced.

As the ring assembly 950 is advanced toward the distal position, thebackup member 976 disengages from the anvil center rod, allowing for theanvil head 940 to pivot relative to the anvil center rod. It iscontemplated that the anvil head 940 may be configured to pivotautomatically relative to the anvil center rod in any manner describedherein. In embodiments, the anvil head 940 may be pivoted via anysuitable pivoting mechanism, whether it is automatic or manual.

With reference to FIG. 55 , a retraction of the annular knife 30 back toits starting position causes the outer body portion 978 b of the cutring 978 to move proximally within the groove 975 due to the frictionalengagement between an outer surface of the annular knife 30 and an innerperipheral surface 979 of the outer body portion 978 b of the cut ring978. The outer body portion 978 b of the cut ring 978 is draggedproximally by the retracting annular knife 30 until the outer bodyportion 978 b of the cut ring 978 contacts the proximal ledge 975 a.With the outer body portion 978 b of the cut ring 978 in contact withthe proximal ledge 975 a, the outer body portion 975 b and the innerbody portion 978 a are axially spaced from one another, creating apassage 982 through which staples lodged in the cut ring 978 may beremoved.

Persons skilled in the art will understand that the devices and methodsspecifically described herein and illustrated in the accompanyingdrawings are non-limiting exemplary embodiments. It is envisioned thatthe elements and features illustrated or described in connection withone exemplary embodiment may be combined with the elements and featuresof another without departing from the scope of the present disclosure.As well, one skilled in the art will appreciate further features andadvantages of the disclosure based on the above-described embodiments.Accordingly, the disclosure is not to be limited by what has beenparticularly shown and described, except as indicated by the appendedclaims.

What is claimed is:
 1. A surgical anvil assembly for use with a circularstapling instrument, comprising: an anvil head defining a recess; abackup member slidably disposed within the recess of the anvil head andselectively engagable with an anvil center rod; and a locking assemblyincluding: an inner member; and an outer member movably coupled to theinner member and coupled to the backup member such that the outer membermoves with the backup member, wherein the outer member is configured tomove relative to the inner member between a proximal position, in whichthe outer member is configured to maintain the backup member in aproximal position, and a distal position, in which the outer member isconfigured to maintain the backup member in a distal position.
 2. Thesurgical anvil assembly according to claim 1, wherein the inner memberis axially fixed relative to the anvil head.
 3. The surgical anvilassembly according to claim 2, wherein the inner member is disposedoutside of the anvil head.
 4. The surgical anvil assembly according toclaim 3, wherein the inner member is supported on a distally-facingouter surface of the anvil head.
 5. The surgical anvil assemblyaccording to claim 1, wherein the locking assembly further includes apost interconnecting the outer member and the backup member.
 6. Thesurgical anvil assembly according to claim 5, wherein the post includes:a distal end disposed outside of the anvil head and fixed to the outermember; an intermediary portion extending through the anvil head; and aproximal end disposed within the recess of the anvil head and fixed tothe backup member.
 7. The surgical anvil assembly according to claim 1,wherein the locking assembly further includes at least one lockingmember protruding outwardly from the inner member and configured toresist without preventing axial movement of the outer member relative tothe inner member.
 8. The surgical anvil assembly according to claim 7,wherein the at least one locking member is configured to engage theouter member when the outer member is in the distal position to maintainthe outer member in the distal position.
 9. The surgical anvil assemblyaccording to claim 7, wherein the at least one locking member isconfigured to resist movement of the backup member from the proximalposition toward the distal position until a threshold, distally-orientedforce is applied to the backup member.
 10. The surgical anvil assemblyaccording to claim 7, wherein the at least one locking member overlapswith an inner lip of the outer member to resist distal movement of theouter member relative to the inner member toward the distal position.11. The surgical anvil assembly according to claim 7, wherein the outermember is configured to flex radially outward as the outer member movesover the at least one locking member from the proximal position towardthe distal position.
 12. The surgical anvil assembly according to claim7, wherein the at least one locking member includes: a first lockingmember extending radially outward from a first side of the inner member;and a second locking member extending radially outward from a secondside of the inner member, the first and second locking membersconfigured to engage an inner periphery of the outer member.
 13. Thesurgical anvil assembly according to claim 7, wherein the at least onelocking member includes a detent configured to engage an inner peripheryof the outer member when the outer member is in the distal position. 14.The surgical anvil assembly according to claim 13, wherein the outermember includes a lip protruding radially inwardly from the innerperiphery thereof, the lip being disposed proximally of the detent whenthe outer member is in the proximal position, such that the detentresists movement of the outer member from the proximal position towardthe distal position.
 15. The surgical anvil assembly according to claim14, wherein the lip is radially aligned with the detent when the outermember is in the distal position, such that the detent resists movementof the outer member from the distal position toward the proximalposition.
 16. The surgical anvil assembly according to claim 13, whereinthe detent is configured to move radially inward upon movement of theouter member toward the distal position, and the detent is configured tomove radially outward upon movement of the outer member toward theproximal position.
 17. The surgical anvil assembly according to claim 1,further comprising a cut ring positioned about the backup member andsecured thereto.
 18. The surgical anvil assembly according to claim 1,further comprising the anvil center rod, wherein the anvil head ispivotally coupled to the anvil center rod and movable between a first,operative condition and a second, tilted condition.
 19. The surgicalanvil assembly according to claim 18, wherein when the outer member isin the proximal position, the locking assembly is configured to maintainthe backup member engaged with the anvil center rod to resist movementof the anvil head out of the first, operative condition, and when theouter member is in the distal position, the locking assembly isconfigured to maintain the backup member out of engagement with theanvil center rod to allow for movement of the anvil head toward thesecond, tilted condition.
 20. A surgical anvil assembly for use with acircular stapling instrument, comprising: an anvil head; a cut ringdisposed within the anvil head; an inner member axially fixed relativeto the anvil head; and an outer member disposed about the inner memberand coupled to the cut ring, wherein the outer member is configured toslide relative to the inner member between a proximal position, in whichthe outer member is configured to maintain the cut ring in a proximalposition, and a distal position, in which the outer member is configuredto maintain the cut ring in a distal position.